Installation structure of seeker window and flying object with seeker window

ABSTRACT

A seeker window includes a transparent plate and a frame structure coupled to a circumference of the transparent plate. An installation structure of the seeker window has a flexible window frame which includes a window frame body section; a flexible section coupled to the window frame body section and the seeker window; and a fastener configured to fix the window frame body section to an inner structure of a nose section of a flying object.

CROSS-REFERENCE

This application claims a priority on convention based on Japanese Patent Application JP 2014-045156 filed on Mar. 7, 2014. The disclosure thereof is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an installation structure of a seeker window for a seeker which is used under a hot environment, and a flying object with the seeker window.

BACKGROUND ART

A seeker window is arranged in the outer shell section in a tip nose section of a flying object having a seeker section and flying in the atmosphere at high speed in the flight, to protect the seeker section. The seeker section is an equipment to acquire the information of a target.

Japanese Patent 2,713,242B2 (Patent Literature 1) discloses a dome for a flying object in which heat conductive members are thermally coupled to the fuselage section of the flying object. In Patent Literature 1, the dome for the flying object is provided with an infrared ray incident section, in which an infrared ray transmission material having a triangular plate shape is incorporated in a skeleton of a multi-angle pyramid of the long heat conductive members, at the tip of the dome.

According to the dome for the flying object disclosed in Patent Literature 1, a heat due to aerodynamic heating which is centralized in the tip of the dome can be radiated effectively with a simple structure.

Also, JP S64-21741U (Patent Literature 2) discloses a viewing port structure of a vacuum apparatus. In a viewing port section disclosed in Patent Literature 2, a flange section is configured of a bonding structure of aluminum alloy member and a stainless steel member. A knife-edge section is disposed on the side of the aluminum alloy member, and a kovar fuselage section is disposed on the side of the stainless steel member. A vacuum apparatus of stainless material is welded to these members.

According to the viewing port section of the vacuum apparatus disclosed in Patent Literature 2, the effective diameter can be made large, and the compact viewing port section can be configured.

CITATION LIST

[Patent Literature 1] Japanese patent 2,713,242B2

[Patent Literature 2] JP S64-21741U

SUMMARY OF THE INVENTION

FIG. 1 is a sectional view showing an installation structure of a seeker window 14 disposed in an inclined surface of a nose section 12 coupled to a fuselage section of the flying object 10. Generally, a resin seal member 918, a holding metal member 900 and a window fixation fastener 20 are used for the installation structure of the seeker window 14.

In the installation structure of the seeker window 14 shown in FIG. 1, the resin seal member 918 is adhered from the inside of the nose section 12. Then, the seeker window 14 is installed from the inside of the nose section 12 so as to push the resin seal member 918. Subsequently, a seal material 919 is applied on the seeker window 14 from the inside of the nose section 12, and the seeker window 14 is fixed by the fastener 20 from the inside of the nose section 12 through the holding metal member 900.

Here, because the linear expansion coefficient differs between the nose section 12 and the seeker window 14, an opening for installation of the seeker window 14 in the nose section 12 needs to be formed to be slightly larger than the outward form of the seeker window 14. The seeker window 14 is pushed against the outer shell structure of the nose section 12 by using the elasticity of the resin seal member 918. In this way, a gap between the seeker window 14 and the outer shell structure of the nose section 12 is filled with the resin seal member 918, while permitting expansion and contraction of the seeker window 14 to the nose section 12.

In the flying object 10 adopting the installation structure of the seeker window 14 shown in FIG. 1, a seeker section can withstand a wind pressure WP which occurs in case of the flight. When the flight speed of the flying object 10 increases, a shock wave is generated from the tip of the nose section 12. The surface of the seeker window 14 receives the aerodynamic heating ADH and becomes hot. At this time, the heat is transferred to the resin seal member 918 to fuse the resin seal member 918, so that airtightness near the seeker window 14 is damaged. Regarding the resin seal member 918 of rubber having elasticity, silicone rubber (heat-resistant limit temperature: 230° C.) and a fluorine resin (heat-resistant limit temperature: 260° C.) are known as material having heat resistance. However, the heat-resistant limit temperatures of them are equal to or less than 300° C.

Also, because the outer surface of the seeker window 14 is heated, a temperature difference occurs between the outer surface side of the seeker window 14 and the inner side of the seeker window 14 in the nose section 12, so that the seeker window 14 curves due to the heat deformation. For the reason of the deformation of the seeker window 14, a problem is caused that the airtightness is degraded around the seeker window 14. In the higher-speed flying object, the installation structure of the seeker window 14 which can endure under a hotter environment is demanded.

Also, in order to endure under the hotter environment in case of the higher-speed flight, it is possible to adopt a restriction type installation structure of the seeker window in which the seeker window 14 is fixed directly on the nose section 12 without using the elasticity of the resin seal member 918. When this restriction type installation structure of the seeker window is adopted, a large unevenness occurs on the surface of the flying object 10 with thermal deformation of the seeker window 14 and the nose section 12, so that the increase of the aerial resistance at the time of flight of the flying object and the degradation of the control performance are caused.

An object of the present invention is to provide an installation structure of a seeker window for a flying object which can endure under a hot environment.

An installation structure of a seeker window is provided. A flying object comprises a fuselage section and a nose section having an opening for the seeker window and coupled to the fuselage section. The seeker window protects a seeker section disposed in the flying object. The seeker window includes: a transparent plate configured to transmit a light of a predetermined wavelength range for the seeker section; and a frame structure coupled to a circumference of the transparent plate. The installation structure includes a flexible window frame which has: a window frame body section; a flexible section coupled to the window frame body section and the seeker window and configured to flexibly deform in response to a deformation of the seeker window; and a fastener configured to fix the window frame body section to an inner structure of the nose section.

Preferably, the installation structure of a seeker window further includes a gasket disposed in a groove that is formed in a surface of the window frame body section facing the inner structure of the nose section, and configured to seal an inside of the nose section from an outer ambience of the flying object.

The window frame body section may be accommodated in an inside of the nose section.

The surface of the window frame body section which opposes to a surface facing the inner structure of the nose section may be exposed to an outer ambience of the flying object.

The flexible section may be formed to have a bottom portion extending from an end surface of the window frame body section to a middle point and a rising portion extending outwardly along the end surface of the window frame body section while being apart from the end surface. The frame structure is tightly coupled to a surface of the rising portion on the seeker window.

Also, the installation structure of a seeker window may further includes a gap seal member filled in a gap between the end surface of the window frame body section and the rising portion of the flexible section.

The gap seal member may have a plurality of plates which are separated from each other. In this case, the plurality of plates may be coupled at a coupling point one after another to have an interval. The coupling point is deeper inwardly than an inner surface of the seeker window.

In addition, another aspect of the present invention, a flying object includes: a fuselage section; and a nose section having an opening for a seeker window and coupled to the fuselage section. The seeker window protects a seeker section disposed in the flying object. The seeker window includes: a transparent plate configured to transmit a light of a predetermined wavelength range for the seeker section; and a frame structure coupled to a circumference of the transparent plate. An installation structure of the seeker window includes a flexible window frame which has: a window frame body section; a flexible section coupled to the window frame body section and the seeker window and configured to flexibly deform in response to a deformation of the seeker window; and a fastener configured to fix the window frame body section to an inner structure of the nose section.

In this case, the installation structure may further includes a gasket disposed in a groove that is formed in a surface of the window frame body section facing the inner structure of the nose section, and configured to seal an inside of the nose section from an outer ambience of the flying object.

Also, the window frame body section may be accommodated in an inside of the nose section.

Also, a surface of the window frame body section which opposes to a surface facing the inner structure of the nose section may be exposed to an outer ambience of the flying object.

The flexible section is desirably formed to have a bottom portion extending from an end surface of the window frame body section to a middle point and a rising portion extending outwardly along the end surface of the window frame body section while being apart from the end surface. The frame structure is tightly coupled to a surface of the rising portion on the seeker window.

The installation structure of the seeker window according to the present invention has an advantage that it is possible to use the flying object in a flight under the hotter environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a conventional installation structure of a seeker window in a nose section near the tip of the flying object.

FIG. 2 is a perspective view of the nose section and a fuselage section of the flying object to which the installation structure of a seeker window according to the present invention is applied.

FIG. 3 is a sectional view showing the installation structure of the seeker window in the nose section coupled to the fuselage section in the flying object.

FIG. 4 is a sectional view showing a state that the seeker window shown in FIG. 3 is deformed thermally.

FIG. 5 is a sectional view showing the installation structure of the seeker window according to another embodiment of the present invention.

FIG. 6 is a sectional view showing the installation structure of the seeker window in which a plate-like gap seal member is arranged in the gap.

FIG. 7 is an outward appearance perspective view showing an example of the gap seal member in which thin plates are laminated.

Description of Embodiments

Hereinafter, an installation structure of a seeker window and a flying object having the seeker window according to embodiments of the present invention will be described with reference to the attached drawings.

FIG. 2 is a perspective view of a nose section 12 coupled to a fuselage section 32 in the tip of a flying object 10. A seeker window 14 is arranged on an inclined surface of the nose section 12 of the flying object 10 to protect a seeker section (not shown) installed in the nose section 12. The nose section 12 has an opening for the seeker window 14 on the inclined surface. The seeker window 14 includes a transparent plate 14 a and a frame structure 14 b. When the flying object 10 flies in a FR direction at high-speed, a shock wave is generated near the tip of the nose section 12, and the outer surface of the seeker window 14 receives aerodynamic heating ADH which increases it to a high temperature.

FIG. 3 is a sectional view showing the installation structure of the seeker window 14 according to a first embodiment of the present invention. FIG. 4 is a sectional view of the installation structure of the seeker window 14 showing a state that the seeker window 14 shown in FIG. 3 has been deformed to a shape protruding outwardly due to a heat.

Referring to FIG. 3, the installation structure includes an inner structure of the nose section 12, the seeker window 14, a flexible window frame 16, a gasket 18, a pushing metal member 22, and a fastener 20.

The transparent plate 14 a protects the seeker section and allows light of a predetermined wavelength range to transmit. Thus, the seeker section seeks a target object or a target position by using the light. The transparent plate 14 a is formed of glass or kovar glass, light transmissive ceramics and so on, and the material of the transparent plate 14 a is selected according to a heatproof temperature.

The frame structure 14 b supports the transparent plate 14 a in the opening for the seeker window 14. The frame structure 14 b is fixed to the circumference of the transparent plate 14 a with gluing and so on. Heat resistant steel such as kovar and SUH446, stainless steel, nickel base alloy, cobalt base alloy, and other materials may be used as the material of the frame structure 14 b.

The flexible window frame 16 includes a flexible section 16 a and a window frame body section 16 b. The flexible section 16 a extends thinly from the window frame body section 16 b to a middle point to and extends outwardly along an end surface of the window frame body section 16 b while being apart from the window frame body section 16 b. Thus, the flexible section 16 a and the window frame body section 16 b form a U-shaped structure, and a gap 17 is formed between the flexible section 16 a and the window frame body section 16 b. The flexible section 16 a can deform such that the flexible section 16 a is brought close to the window frame body section 16 b when the seeker window 14 deforms due to a heat expansion. In this case, the flexible section 16 a may first extend laterally or outwardly and then outwardly, or inwardly once and then outwardly. In such a case, the bottom point of the bending portion functions as a fulcrum point. Note that the rising section of the flexible section 16 a is not limited to form the U-shaped section. By forming the flexible section 16 a as a part of the flexible window frame 16, it is possible to reduce the stress which is applied to the seeker window 14 and the nose section 12 when the heat deformation is large.

Also, the gap 17 is formed between the flexible section 16 a and the window frame body section 16 b to absorb a size change due to the heat deformation of the seeker window 14 and the nose section 12. When any step or unevenness exists on the surface of the flying object 10, there is a possibility that the distortion of the air current and the fluid force occur near the window at the time of the flight.

However, in the first embodiment, the surface of the nose section 12, the flexible window frame 16, and the seeker window 14 around the gap 17 of the flying object 10 is formed to have no step. Note that in the first embodiment, an example that the gap 17 is formed perpendicularly to the surface of the fuselage 12. However, the present invention is not limited to the present embodiment that the gap 17 is formed as a perpendicular ditch or slit, and the ditch or slit may be diagonally formed.

The flexible window frame 16 is disposed around the seeker window 14. The flexible section 16 a may be formed wholly or partially around the circumference of the seeker window 14. The seeker window 14 is tightly fixed on the flexible section 16 a with a brazing method, a gluing method and so on. The frame structure 14 b of the seeker window 14 is coupled to a tip portion of the flexible section 16 a which is near to the outer surface of the nose section 12.

A surface 16 c of the window frame body section 16 b contacts the inner surface of a flange of the nose section 12. A groove is formed in the surface 16 c of the window frame body section 16 b, and the gasket 18 is located in the groove. Thus, the gasket 18 is flexibly deformed by the window frame body section 16 b and the flange of the nose section 12. In this way, in the first embodiment, the gasket is disposed with no relation to the transparent plate 14 a. The deformed gasket 18 maintains airtightness and liquid tightness between the nose section 12 and the window frame body section 16 b. In the first embodiment, because a function to absorb heat deformation between the nose section 12 and the seeker window 14 is not required to the gasket 18, the groove as a gasket disposing groove is formed in the window frame body section 16 b and the gasket 18 having a circular section is disposed in it. By this structure, a material in a wide range such as metal, polyamide fiber, fiber glass, silicon rubber, fluorine system resin and so on can be used for the gasket 18, and the proper gasket is selected according to the temperature condition. Also, the gasket 18 having a hollow section or a flat plate shape may be used.

A surface 16 d of the window frame body section 16 b contacts a surface of the nose section 12 connected to the flange.

The pushing metal member 22 pushes a surface 16 e of the window frame body section 16 b so that the surface 16 c is pushed against the inner surface of the flange of the nose section 12. In this condition, the fastener 20 fixes the pushing metal member 22 to the inner structure of the nose section 12. In the first embodiment, an assembly of the seeker window 14, the flexible window frame 16 and the gasket 18 is attached to the predetermined opening of the nose section 12 from the inside of the nose section 12, and is fixed by using the pushing metal member 22 and the fastener 20. Thus, the assembly is accommodated in the inside of the nose section 12.

Next, the heat deformation of the seeker window 14 when the flying object 10 becomes hot due to aerodynamic heating ADH will be described with reference to FIG. 4. When the outer surface H of the transparent plate 14 a of the seeker window 14 is heated through the aerodynamic heating ADH, a temperature difference occurs between the outer surface H and the inner surface C of the transparent plate 14 a. In this case, as shown in FIG. 4, a deformation in which a convex shape is generated to protrude outwardly occurs to the transparent plate 14 a of the seeker window 14.

As shown in FIG. 4, even if the transparent plate 14 a of the seeker window 14 is deformed to have the convex shape protruding outwardly (curve deformation) and a large elastic deformation occurs to the nose section 12 or the seeker window 14, the stress which occurs in the nose section 12 and the seeker window 14 can be reduced through flexion deformity of the flexible section 16 a. Thus, the deformation of the surface of the flying object 10 can be made little. Also, by forming the gap 17 which has the ditch or slit on the outer surface of the flying object 1, the stress of the nose section 12 and the seeker window 14 can be reduced without hindering deformation between the nose section 12 and the seeker window 14. Also, the larger seeker window 14 becomes able to be formed.

The gap 17 is appropriately determined according to the linear expansion coefficients and the expected temperatures of the nose section 12 and the seeker window 14. When the linear expansion coefficients of the nose section 12 and the seeker window 14 are substantially equal to each other, little change of the gap 17 due to the temperature rise occurs. When the linear expansion coefficient of the nose section 12 is larger than that of the seeker window 14, and when the nose section 12 becomes hotter, the gap 17 is set to be made wider as the expected temperature rises.

According to the first embodiment, the heat deformation of the seeker window 14 is permitted to a degree. Therefore, by forming the frame structure 14 b to be thin (a width between the flexible window frame 16 and the transparent plate 14 a) so that the stress is difficult to be applied to the transparent plate 14 a, materials in which the linear expansion coefficients are different between the frame structure 14 b and the transparent plate 14 a can be used. Note that the durability to repetitive deformation is required in the equipment for a long-term use, but when the flexible window frame 16 is used as an attachment structure of the seeker window 14, the durability to the heat deformation and the fatigue are unnecessary.

Next, another installation structure in which the seeker window 14 is installed to the slope of the nose section 12 near the tip of the flying object 10 according to a second embodiment of the present invention will be described with reference to FIG. 5. Note that the same reference numeral is assigned to a part which has the same function as described in FIG. 1 to FIG. 3. Thus, the description is omitted.

In the first embodiment, the assembly of the seeker window 14 and the flexible window frame 16 is fixed from the inside of the nose section 12. On the other hand, in the second embodiment, an assembly of the seeker window 14 and the flexible window frame 16 is installed from the outside of the nose section 12 and the fastener 20 is fastened from the inside of the fuselage 12.

The surface 16 c of the flexible window frame 16 is not involved in the nose section 12 but exposed to the outer ambient in the second embodiment. Also, any groove for housing the gasket is not formed in the surface 16 c. Instead, a groove is formed in the surface 16 e of the flexible window frame 16. By fastening the fastener 20 to the inner structure of the nose section 12, the surface 16 e of the flexible window frame 16 is fixed to the inner structure of the nose section 12.

As shown in FIG. 5, by using the installation structure of the seeker window 14 according to the second embodiment, the assembly of the seeker window 14 and the flexible window frame 16 can be assembled from outside the nose section 12 and the workability at the time of the assembly is improved.

Next, with reference to FIG. 6, the installation structure of the seeker window 14 according to a third embodiment of the present invention will be described. Note that a same reference numeral is assigned to a part which has the same function as in the first and second embodiments. Thus, the description is omitted.

In the third embodiment, a plate-like gap seal member 19 is arranged in the gap 17 of the flexible window frame 16 to improve the smoothness of the surface of the flexible window frame 16 from the nose section 12 to the seeker window 14. As the gap seal member 19, laminated thin plates are arranged in the gap 17, so that the ends of the laminated thin plates are exposed from the surface of the flying object 10. Thus, the smoothness of the surface of the nose section 12 is improved without obstructing the flexibility of the flexible section 16 a.

For example, as shown in FIG. 7, the gap seal member 19 may be used in which a plurality of thin metal plates 19 a are laminated and fixed by a spot welding, a brazing, or a gluing in bonding sections 19 b, to have a predetermined interval. Thus, it is possible to form a small gap between adjacent two of the plates and to give a flexible deformation property to the plates. By using such a gap seal member 19, it is possible to improve the flexibility and the deformation performance compared with a case of using a solid material. By arranging such a gap seal member 19 in the gap 17, it is possible to fill the gap 17 to an extent without obstructing the flexion deformity and to reduce aerial resistance in case of the flight of the flying object 10. In this case, the bottom of the U-shaped ditch of the flexible section 16 a is deeper than the inner surface of the transparent plate 14 a and the window frame body section 14 b. Accordingly, when the seeker window 14 expands due to the heat, a portion of the flexible section 16 a near to the outer surface is deformed by pushing of the seeker window 14, so that the expansion of the seeker window 14 can be absorbed.

Note that an expansion graphite which has flexibility in addition to a high heat resistance may be used as the material of the gap seal member 19 and it may be filled in the gap 17.

As above, the installation structure of the seeker window and the flying object with the seeker window according to the present invention have been described reference to the embodiments. However, the installation structure of the seeker window and the flying object with the seeker window according to the present invention are not limited to the above embodiments. Various modifications can be carried out to the above embodiments. One or more of the embodiments and one or more of the other embodiments may be combined. 

What is claimed is:
 1. An installation structure of a seeker window, wherein a flying object comprises a fuselage section and a nose section having an opening for said seeker window and coupled to said fuselage section, wherein said seeker window protects a seeker section disposed in said flying object, wherein said seeker window comprises: a transparent plate configured to transmit a light of a predetermined wavelength range for said seeker section; and a frame structure coupled to a circumference of said transparent plate, and wherein said installation structure comprises a flexible window frame which comprises: a window frame body section; a flexible section coupled to said window frame body section and said seeker window and configured to flexibly deform in response to a deformation of said seeker window; and a fastener configured to fix said window frame body section to an inner structure of said nose section.
 2. The installation structure of a seeker window according to claim 1, further comprising a gasket disposed in a groove that is formed in a surface of said window frame body section facing said inner structure of said nose section, and configured to seal an inside of said nose section from an outer ambience of said flying object.
 3. The installation structure of a seeker window according to claim 1, wherein said window frame body section is accommodated in an inside of said nose section.
 4. The installation structure of a seeker window according to claim 1, wherein a surface of said window frame body section which opposes to a surface facing said inner structure of said nose section is exposed to an outer ambience of said flying object.
 5. The installation structure of a seeker window according to claim 1, wherein said flexible section is formed to have a bottom portion extending from an end surface of said window frame body section to a middle point and a rising portion extending outwardly along the end surface of said window frame body section while being apart from the end surface, and wherein said frame structure is tightly coupled to a surface of said rising portion on said seeker window.
 6. The installation structure of a seeker window according to claim 5, further comprising: a gap seal member filled in a gap between the end surface of said window frame body section and said rising portion of said flexible section.
 7. The installation structure of a seeker window according to claim 6, wherein said gap seal member comprises a plurality of plates which are separated from each other.
 8. The installation structure of a seeker window according to claim 7, wherein said plurality of plates are coupled at a coupling point one after another to have an interval, and wherein the coupling point is deeper inwardly than an inner surface of said seeker window.
 9. A flying object comprising: a fuselage section; and a nose section having an opening for a seeker window and coupled to said fuselage section, wherein said seeker window protects a seeker section disposed in said flying object, wherein said seeker window comprises: a transparent plate configured to transmit a light of a predetermined wavelength range for said seeker section; and a frame structure coupled to a circumference of said transparent plate, and wherein an installation structure of said seeker window comprises a flexible window frame which comprises: a window frame body section; a flexible section coupled to said window frame body section and said seeker window and configured to flexibly deform in response to a deformation of said seeker window; and a fastener configured to fix said window frame body section to an inner structure of said nose section.
 10. The flying object according to claim 9, wherein said installation structure further comprises a gasket disposed in a groove that is formed in a surface of said window frame body section facing said inner structure of said nose section, and configured to seal an inside of said nose section from an outer ambience of said flying object.
 11. The flying object according to claim 9, wherein said window frame body section is accommodated in an inside of said nose section.
 12. The flying object according to claim 9, wherein a surface of said window frame body section which opposes to a surface facing said inner structure of said nose section is exposed to an outer ambience of said flying object.
 13. The flying object according to claim 9, wherein said flexible section is formed to have a bottom portion extending from an end surface of said window frame body section to a middle point and a rising portion extending outwardly along the end surface of said window frame body section while being apart from the end surface, and wherein said frame structure is tightly coupled to a surface of said rising portion on said seeker window.
 14. The flying object according to claim 13, wherein said installation structure further comprises: a gap seal member filled in a gap between the end surface of said window frame body section and said rising portion of said flexible section.
 15. The flying object according to claim 14, wherein said gap seal member comprises a plurality of plates which are separated from each other.
 16. The flying object according to claim 15, wherein said plurality of plates are coupled at a coupling point one after another to have an interval, and wherein the coupling point is deeper inwardly than an inner surface of said seeker window. 